Thursday, September 16, 2010

Update - projected US temperatures in 2050

An update on the answer to the question: "What will US temperatures be in 2050?"

The gnomes that keep the temperature data add new years and massage/tweak/fudge/adjust (take your choice) the data from time to time. That is, the figure they give for the Temperature Difference in, for example, 1934 decreased from 1.25 to 1.20 between 2007 and 2010 (??). Also, according to their new figures, the average Temperature Difference in the years 1995-2005 increased from 0.53 C to 0.67 C between 2007 and 2010. Go figure. (Hint: adjusting/fudging the older temperatures downward, and the newer temperatures upward, makes it appear that current temperatures are relatively high by historical standards.)

Anyway, let's use their current data posted at http://data.giss.nasa.gov/gistemp/graphs/Fig.D.txt
and go through the same regression as before. I won't bother with the details of the calculations; see the August 19, 2007 post for these. Here's the results, using their data from 1880-2009:
In 2050, the Temperature Difference is now projected to be 0.74 °C (1.3 °F).
The Temperature Difference is expected to rise by 1 °C (1.8 °F) about every 160 years (that is, the slope of the temperature vs. year line is 0.0063.

The 2007 regression projected the 2050 Temperature Difference to be 0.58 °C (1.06 °F)with the 95% confidence interval 0.35 °C to 0.82 °C (0.64 °F to 1.48 °F). So the new prediction is well within the uncertainty of the 2007 projection.

Here's the conclusion from the 2007 projection:
"The linear regression predicts that the US temperature difference in 2050 (0.58 °C or 1.06 °F) will be essentially the same as it was in the years 1995-2005 (0.53 °C or 0.95 °F). A bit warmer than the average since 1880, but not exactly a big deal."

And here's the conclusion from the current projection (remembering that the 1995-2005 figures were adjusted/fudged upwards by the gnomes who do these things):
The linear regression predicts that the US Temperature Difference in 2050 (0.74 °C or 1.3 °F) will be essentially the same as it was in the years 1995-2005 (0.67 °C or 1.2 °F). A bit warmer (about 1 °F) than the average since 1880, but not exactly a big deal.

So if a global warming (oops! - the term is now "climate change") advocate comes to you and says that the Himalayan glaciers will disappear by 2035 (oops again! - they've already retracted that prediction) or that the US temperatures in 2050 will be radically higher than now, ask them to put their money where their mouth is. Suggest they bet you, say, $1 million in inflation-adjusted dollars at even odds that the average Temperature Difference in 2045-2055 will be more than 3 °C or 5 °F higher than in 1995-2005, with the bet being binding on the heirs of both of you. Then sit back and wait to collect your money, or to give your children or grandchildren a nice nest egg.

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